This invention relates to an adsorption process for the separation of steam and less readily adsorbable component e.g. CO.sub.2 from a gaseous stream e.g. air wherein hot scavenging gas is employed to regenerate the adsorbent. (Where the term "steam" is used herein, it is meant to include water molecules in the gaseous phase at any temperature and in any concentration, thus for example embracing the humidity of room temperature air.)
In a conventional process of this type, described in DAS No. 2,064,137 and citing as the important feature the use of zeolitic molecular sieve as the adsorbent, the energy consumption for regeneration of the loaded adsorbent is reduced by providing that the temperature of the hot scavenging gas, instead of the usual 200.degree.-300.degree. C., be less than 200.degree. C., scavenging gas temperatures down to 80.degree. C. being set forth. However, it was found under practical conditions that the calculations forming the basis for DAS No. 2,064,137 were too optimistic, for the molecular sieve intended as the adsorbent could no longer be satisfactorily desorbed at scavenging gas temperatures of below 150.degree. C. Therefore, modern plants for the separation of steam and carbon dioxide from gaseous streams operate with a scavenging gas temperature of about 170.degree. C. Examples of such processes are, inter alia, the pretreatment of gaseous streams to be subjected to a low-temperature process in order to prevent the danger of troublesome solid deposits, for example in cryogenic air fractionation, in the processing of natural gas, synthesis gases, or cracked gases.